Method and apparatus for data transfer using a time division multiple frequency scheme

ABSTRACT

A method of data transmission according to one embodiment of the invention includes encoding a set of data values to produce a corresponding series of ordered n-tuples. The method also includes transmitting, according to the series of ordered n-tuples, a plurality of bursts over a plurality n of frequency bands. Specifically, for each of the plurality of bursts, a frequency band occupied by the burst is indicated by the order within its n-tuple of an element corresponding to the burst. A bandwidth of at least one of the plurality of bursts is at least two percent of the center frequency of the burst.

RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional PatentApplications No. 60/326,093 (“FREQUENCY SHIFT KEYING WITH ULTRAWIDEBANDPULSES,” filed Sep. 26, 2001); No. 60/359,044 (“POLARITY SIGNALINGMETHODS BASED ON TDMF UWB WAVEFORMS,” filed Feb. 20, 2002); No.60/359,045 (“CHANNELIZATION METHODS FOR TIME-DIVISION MULTIPLE FREQUENCYCOMMUNICATION CHANNELS,” filed Feb. 20, 2002); No. 60/359,064 (“HYBRIDSIGNALING METHODS BASED ON TDMF UWB WAVEFORMS,” filed Feb. 20, 2002);and No. 60/359,147 (“TRANSMITTER AND RECEIVER FOR A TIME-DIVISIONMULTIPLE FREQUENCY COMMUNICATION SYSTEM,” filed Feb. 20, 2002).

BACKGROUND

[0002] 1. Field of the Invention

[0003] This invention relates to data transfer over wired, wireless,and/or optical transmission channels.

[0004] 2. Background Information

[0005] As computing and communications applications become richer andmore complex, it becomes desirable to support transfers of data betweendevices at higher and higher rates. The increasing popularity ofconsumer electronics, computing, and communicating devices, in variousforms (e.g. mobile, hand-held, wearable, and fixed) and possibly withassociated peripherals, indicates a clear demand for these types ofdevices and for connectivity (e.g. peer-to-peer and/or networked)between them. Unfortunately, present-day communications technologiesfall short of providing the technical requirements necessary to supportsuch demands.

[0006] Wireless connectivity may enable greater user experiences andpossibly spur an increased demand for such devices. For example,wireless connectivity can provide enhanced capability; is expected to beeasier to use; may encompass cost savings and increases in efficiencyand productivity; and may increase possible device applications and/ordeployments.

[0007] Use of such devices may include large data transfers and/ormultimedia applications. For example, a cable replacement scenario for acomputer, a consumer electronics device, or a similar device may need tosupport transfers of large amounts of data. Multimedia applications mayhandle multiple simultaneous streams of high-definition audio and/orvideo coming from devices such as business/entertainment systems andgateways.

[0008] Most existing wireless schemes transfer data via modulatedcontinuous-wave carriers. In many cases, a portion of theradio-frequency spectrum is reserved for the exclusive use of thescheme. Such reservations allow these transfer schemes (e.g. commercialradio and TV broadcasts) to operate free of interference from otherdevices and without interfering with other systems.

[0009] Data transfers may be conducted over very narrow frequency bandsin an attempt to occupy less of the frequency spectrum. However, suchschemes may be more susceptible to increases in background noise leveland to multipath interference. Some narrowband schemes may also be morelikely to interfere with other systems (e.g. due to a higherconcentration of energy in the particular frequency band being used).

[0010] Although battery technology is steadily improving, operatingtimes between charges or replacement are still important factors in thedesign of portable devices. Complexity and cost of transmitter andreceiver implementations are other important factors for consumerapplications. Present-day solutions offer only a few of the necessarytechnical requirements. For example, some may provide low cost and lowpower consumption but only at low bit rate, while others may have higherbit rates but be unacceptable in terms of cost and/or rate of powerconsumption.

[0011] It is desirable to support high rates of data transfer. It mayalso be desirable for a scheme that supports high, medium, and/or lowrates of data transfer to obtain one or more advantages such as 1) lowpower consumption, 2) low cost of implementation, and/or 3) an abilityto coexist with interferers and/or with other frequency use. Otherdesirable advantages may include scalability with potential capabilityfor backwards compatibility and/or an ability to determine positionand/or location.

SUMMARY

[0012] A method of data transmission according to one embodiment of theinvention includes encoding a set of data values to produce acorresponding series of ordered n-tuples. The method also includestransmitting, according to the series of ordered n-tuples, a pluralityof bursts over a plurality n of frequency bands. Specifically, for eachof the plurality of bursts, a frequency band occupied by the burst isindicated by the order within its n-tuple of an element corresponding tothe burst. A bandwidth of at least one of the plurality of bursts is atleast two percent of the center frequency of the burst. Methods of datareception and transmitter and receiver configurations are alsodisclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 shows examples of three ultra-wideband bursts at differentfrequencies.

[0014]FIG. 2 shows the three bursts of FIG. 1 in the frequency domain.

[0015]FIG. 3 shows a timing diagram.

[0016]FIG. 4 shows a timing diagram.

[0017]FIG. 5 shows a sequence of three ultra-wideband bursts in time.

[0018]FIG. 6 shows the sequence of FIG. 5 in the frequency domain.

[0019]FIG. 7 shows a time-domain plot of overlapping ultra-widebandbursts.

[0020]FIG. 8 shows a flowchart of a method according to an embodiment ofthe invention.

[0021]FIG. 9 shows one example of an ordered set of m data values and acorresponding series of ordered n-tuples.

[0022]FIG. 10 shows a representation of one correspondence between anencoded symbol and burst activity over time slots and across differentfrequency bands for the series of FIG. 9.

[0023]FIG. 11 shows another representation of a correspondence betweenencoded symbols and burst activity over time slots and across differentfrequency bands.

[0024]FIG. 12 shows a diagram of an application in which bursts indifferent frequency bands are transmitted at different times.

[0025]FIG. 13 shows an effect of random time perturbation in clustertransmission start time.

[0026]FIG. 14 shows an example of a scheme in which symbols for twodifferent logical channels are transmitted over the same physicalchannel at different times.

[0027]FIG. 15 shows an example of a scheme in which symbols for twodifferent logical channels are transmitted over the same physicalchannel at the same time.

[0028]FIG. 16 shows a block diagram of a transmitter 100 according to anembodiment of the invention.

[0029]FIG. 17 shows a block diagram of an implementation 150 oftransmitter 100.

[0030]FIG. 18 shows a block diagram of an implementation 110 oftransmitter 100.

[0031]FIG. 19 shows a block diagram of an implementation 410 ofserializer 400.

[0032]FIG. 20 shows a block diagram of an implementation 420 ofserializer 400.

[0033]FIG. 21 shows a block diagram of an implementation 120 oftransmitter 100.

[0034]FIG. 22 shows a block diagram of an implementation 222 of encoder220.

[0035]FIG. 23 shows an implementation 302 of signal generator 300.

[0036]FIG. 24 shows trigger pulses on N independent trigger signals asgenerated by trigger generator 320.

[0037]FIG. 25 shows a block diagram of signal generator 302 and animplementation 452 of signal launcher 450.

[0038]FIG. 26 shows a block diagram of an implementation 303 of signalgenerator 302.

[0039]FIG. 27 shows an implementation 304 of signal generator 300.

[0040]FIG. 28 shows a block diagram of signal generator 304 and animplementation 454 of signal launcher 450.

[0041]FIG. 29 shows a block diagram of signal generator 306 and animplementation 456 of signal launcher 450.

[0042]FIG. 30 shows a correspondence between waveform profiles in thetime and frequency domains.

[0043]FIG. 31 shows a spectral plot of a sequence of bursts.

[0044]FIG. 32 shows a spectral plot of a sequence of bursts.

[0045]FIG. 33 shows a block diagram of an oscillator 342 according to anembodiment of the invention.

[0046]FIG. 34 shows a block diagram of an implementation 344 ofoscillator 342.

[0047]FIG. 35 shows a block diagram of an implementation 346 ofoscillator 342.

[0048]FIG. 36 shows a block diagram of an implementation 348 ofoscillator 342.

[0049]FIG. 37 shows a block diagram of an implementation 350 ofoscillator 342.

[0050]FIG. 38 shows a block diagram of an implementation 352 ofoscillator 342.

[0051]FIG. 39 shows a block diagram of an implementation 356 ofoscillator 342 and a compensation mechanism 495.

[0052]FIG. 40 shows a block diagram of an implementation 358 ofoscillator 342 and an implementation 496 of compensation mechanism 495.

[0053]FIG. 41 shows a block diagram of oscillator 358 and animplementation 498 of compensation mechanism 495.

[0054]FIG. 42 shows a block diagram of an implementation 354 ofoscillator 342.

[0055]FIG. 43 shows a block diagram of an implementation 360 ofoscillator 342 according to an embodiment of the invention.

[0056]FIG. 44 shows a block diagram of a receiver 400 according to anembodiment of the invention.

[0057]FIG. 45 shows a block diagram of a burst detector.

[0058]FIG. 46 shows a block diagram of an implementation 450 a of edgedetector 450.

[0059]FIG. 47 shows a block diagram of an implementation 532 of ADC 530that includes a comparator.

[0060]FIG. 48 shows a block diagram of a receiver 401 according to anembodiment of the invention including an implementation 412 of signaldetector 410.

[0061]FIG. 49 shows a block diagram of an implementation 450 b of edgedetector 450.

[0062]FIG. 50 shows a block diagram of a receiver 402 according to anembodiment of the invention including an implementation 414 of signaldetector 410.

[0063]FIG. 51 shows a block diagram of a receiver 403 according to anembodiment of the invention.

[0064]FIG. 52 shows a block diagram of a receiver 404 according to anembodiment of the invention.

[0065]FIG. 53 shows a block diagram of a receiver 405 according to anembodiment of the invention.

[0066]FIG. 54 shows a block diagram of a receiver 406 according to anembodiment of the invention.

[0067]FIG. 55 shows a block diagram of a receiver 407 according to anembodiment of the invention.

[0068]FIG. 56 shows a block diagram of a receiver 408 according to anembodiment of the invention.

[0069]FIG. 57 shows a block diagram of a receiver 409 according to anembodiment of the invention.

[0070]FIG. 58 shows a block diagram of a receiver 4091 according to anembodiment of the invention.

[0071]FIG. 59 shows examples of several bursts and their centerfrequencies.

DETAILED DESCRIPTION

[0072] In the description and claims that follow, certain terms may bedefined as follows:

[0073] The term ‘frequency band’ denotes a portion of the frequencyspectrum. The term ‘center frequency’ as applied to a frequency banddenotes a frequency at the arithmetic mean of the frequencies of theboundaries of the frequency band. As defined herein, frequency bands maybe adjacent to one another but are distinct from one another and do notoverlap.

[0074] The term ‘burst’ denotes the emission of an amount of energywithin a particular range of frequencies and over a limited period oftime. A burst may include one or more cycles of a waveform (e.g. a sinewave). A burst may even be limited to less than one cycle of a waveform.In some applications, two or more bursts may be transmittedsimultaneously. Beginning the transmission of a burst is also referredto as ‘triggering’ the burst. Transferring a burst from the generatingcircuitry (e.g. as described herein) to the transmission medium orchannel is also referred to as ‘launching’ the burst.

[0075] The term ‘bandwidth’ denotes a continuous range of frequenciesthat contains at least 90% and not more than 95% of the total energy ofa signal. The bandwidth of a burst may lie within more than onefrequency band at a time. The term ‘center frequency’ as applied to aburst denotes the midpoint (along the frequency axis) of the energydistribution of the burst: i.e. the frequency at which the total energyof the burst on either side is fifty percent of the total energy of theburst (as in the examples illustrated in FIG. 59). A burst ‘occupies’ afrequency band when the center frequency of the burst is within thefrequency band, such that a burst occupies no more than one frequencyband at a time.

[0076] The term ‘wideband’ denotes a signal whose bandwidth is not lessthan 2% of its center frequency, and the term ‘ultra-wideband’ denotes asignal whose bandwidth is not less than 20% of its center frequency. Forexample, the bandwidth of an ultra-wideband signal may be up to 50% ormore of the signal's center frequency. Ultra-wideband signals may beused at frequencies from less than tens of hertz to terahertz andbeyond. Although most ultra-wideband use currently falls between 100 MHzand 10 GHz primarily due to present-day regulatory allocations, it isenvisioned that future allocations will extend far beyond this frequencyrange.

[0077]FIG. 1 shows an example in the time domain of bursts in threedifferent frequency bands. FIG. 2 shows an alternative representation ofthese three bursts in the frequency domain, where frequency bands 4, 5,and 6 correspond to waveforms 1, 2, and 3, respectively. In thisexample, the three frequency bands are easily distinguished from oneanother in the frequency domain.

[0078] The term ‘time slot’ denotes a defined period of time thatseparates moments at which bursts may be triggered. It may be desirableto observe a convention of triggering bursts only at the start of a timeslot, such that during each time slot, no more than one burst istriggered per frequency band.

[0079] A period of time may be divided into a continuous series ofconsecutive and non-overlapping time slots of equal duration.Alternatively, sets of consecutive and non-overlapping time slots of oneduration may be separated in time by one or more time slots of adifferent (e.g. a longer or even a shorter) duration. In a complexhigh-speed system, the length of a time slot may be measured inpicoseconds. In a lower-speed system of less complexity, the length of atime slot may be in the nanosecond range. In other applications, timeslots of shorter or greater length may be used as desired.

[0080] In the implementations described herein, the same time slotboundaries are observed across the various frequency bands. However, itis contemplated that two or more different time slot arrangements may beapplied among the various frequency bands (e.g. that time slots in onefrequency band may be longer than time slots in another frequency band,or that time slots in one frequency band may have constant length whiletime slots in another frequency band have varying length) in otherimplementations.

[0081]FIG. 3 is an illustration of two examples in which sets of timeslots are separated by periods during which no bursts are launched(‘quiet time’). In example 3A (where different shadings indicatedifferent frequency bands), each burst has a duration shorter than thatof a time slot. However, it is also contemplated that in someapplications a burst may have a duration longer than a time slot (e.g.as in example 3B), such that two or more bursts may overlap even iftheir corresponding time slots do not. In such cases, a series of burststriggered during consecutive time slots in the same frequency band mayrepresent different information than a single burst that extends overthe same number of time slots.

[0082] The term ‘symbol’ denotes an ordered series of n-tuples thatcorresponds to an ordered set of data values. The term ‘cluster’ denotesa set of bursts corresponding to a symbol. The term ‘symbol interval’denotes the period between the start of transmission of a cluster andthe start of transmission of the next cluster and includes any ‘quiettime’ between the clusters. These terms are also illustrated by examplein FIG. 3 and in FIG. 4, which shows consecutive clusters that eachinclude overlapping bursts. In some applications as described herein, itis possible for no bursts to be launched during one or more of the timeslots in each cluster.

[0083] ‘Quiet time’ periods between clusters may be especially useful,for example, in asynchronous applications. In such cases, it may bedesirable for the duration of a quiet time period to be greater than theduration of a time slot.

[0084] In some applications, clusters may not overlap (e.g., to reduceinterference). FIG. 5 shows one example of a cluster that includes threebursts triggered at consecutive time slots. In this example, the startof each burst is delayed by about 2.5 nanoseconds from the start of theprevious burst.

[0085]FIG. 6 shows the cluster of FIG. 5 in the frequency domain.Although the three bursts overlap in frequency, they may still bedistinguished at, e.g., their center frequencies. FIG. 7 shows atime-domain plot of a cluster that includes bursts which overlap intime. In some applications, bursts that overlap in time may be used(e.g. to support higher rates of data transfer) and/or bursts thatoverlap in frequency may be used (e.g. to support higher data density).

[0086]FIG. 8 shows a flowchart of a method according to an embodiment ofthe invention. Task T100 encodes an ordered set (e.g. ordered in timeand/or place) of m data values (e.g. data bits) into a symbol thatincludes a series of p ordered n-tuples (where m and p are integersgreater than zero, and n is an integer greater than one). Task T200transmits the symbol as a cluster that includes a time sequence ofbursts across n frequency bands and over p time slots. For example, taskT200 may transmit the symbol such that the i-th element of each n-tuplecorresponds to the i-th frequency band, and the j-th n-tuple correspondsto the j-th time slot. According to the particular application, overlapin time of bursts on different frequency bands may or may not bepermitted in task T200.

[0087] In an operation of data transfer according to an implementationof this method, the (i,j)-th element of the series of n-tuples indicatesactivity on the i-th frequency band during the j-th time slot. In a baseimplementation, each element is binary-valued, such that its valueindicates either a presence (e.g. ‘1’ or ‘high’) or an absence (e.g. ‘0’or ‘low’) of a burst. In this base implementation, it is also assumedthat a length of each burst is arbitrarily less than one time slot, thata polarity of each burst is constant or arbitrary, and that (e.g. forfree space and optical applications) a polarization of the transmittedbursts is arbitrary. It is specifically contemplated that in otherimplementations, additional information may be supplied (e.g. encodedwithin the series of n-tuples, or provided in addition to such series)to indicate such qualities of a burst or cluster as amplitude, width,polarity, and/or polarization.

[0088] Task T100 may be performed by mapping the ordered set of m datavalues into one of the possible symbol states for the selected encodingscheme. FIG. 9 illustrates such an encoding for one scheme in which eachsymbol has four n-tuples. In this particular example, the n-tuples areconstrained such that two and only two elements of each n-tuple arehigh-valued, with the other values of the n-tuple being low-valued. Sucha restriction may be observed in practice, for example, to maintain aconstant or relatively constant level of energy during transmission of astream of clusters across the transmission channel.

[0089] In such a scheme, each n-tuple has (four choose two) or sixpossible states, as set forth in the table in FIG. 9. The number ofpossible states for each symbol in this case is equal to the number ofstates per n-tuple, raised to the power of the number of time slots(here, 64 or 1296 possible states).

[0090]FIG. 9 includes a flowchart that demonstrates an example ofencoding a 10-bit binary number into a series of four ordered 4-tuplesaccording to this scheme. By way of explanation, FIG. 9 shows this taskas a two-step procedure. First, the input string is converted from aten-digit number in base two to a four-digit number in base six. Second,each of the four digits of the base-six intermediate result is mapped toa corresponding n-tuple state as shown in the table, yielding theencoded symbol as a series of 4 ordered 4-tuples (the mapping shown inthe table is only one of many possible different mappings). While inthis example each n-tuple has a one-to-one correspondence with a digitof the base-six intermediate result, at least some of the elements ofthe n-tuples have a one-to-many correspondence with the values of thebinary input string. Therefore, an n-tuple may represent informationthat relates to more than one of the input data values.

[0091] Note that the two-step procedure of FIG. 9 is shown by way ofexample only. In practice, task T100 may map the input set directly to acorresponding output series using, e.g., a lookup table or equivalentarrangement of combinatorial logic elements.

[0092]FIG. 10 shows a pictorial representation of the distribution ofthe symbol of FIG. 9 over corresponding frequency bands and time slotsaccording to one possible distribution scheme. Note that this particularsymbol indicates activity in frequency band one during all four timeslots. Depending upon the application, this indication will correspondunambiguously to one burst that is active in four consecutive timeslots, or to two bursts that are each active in two consecutive timeslots (or respectively in one and three consecutive time slots), or tofour bursts that are each active in one time slot. As noted above, weassume in this example that the indication corresponds to four separatebursts. FIG. 11 shows a similar representation of a sequence of clustersover time.

[0093] In some schemes, the input set may have fewer possible statesthan the output symbol. In the scheme illustrated in FIG. 9, forexample, each input set of 10 bits may have 2¹⁰ or 1024 differentstates, while each corresponding output symbol may have 6⁴ or 1296different states. While the additional output states (272 states persymbol in this case) may be ignored in some applications, in otherapplications they may be used to carry information. For example, thesestates may be used to transfer information such as one or moreadditional data streams, possibly at a different data transfer rate.

[0094] In one example as applied to the scheme of FIG. 9, 256 of the 272additional states are used to carry a different input stream of 8-bitwords (each word having 2⁸ or 256 possible states), while the remaining16 additional states could even be used to carry a third input stream of4-bit words (each word having 2⁴ or 16 possible states). Alternatively,symbols not used for data can be used to convey control information fromtransmitter to receiver. For example, one or more otherwise unusedsymbol states can be used for synchronization or other timing purposes,to control a decoder initial state, to indicate a change in modulationscheme, etc. In some cases, one or more unmapped symbol states may beused to maintain signal activity or homogeneity (i.e. for transmissionduring a period when no input data is available for transfer).

[0095] In some applications, symbol states that are not mapped to inputsets may be used for signal source identification. For example, one ormore unused symbol states may be assigned to a transmitter for use as anidentifier. A signal that includes this symbol or symbols may then bedistinguished from the signals of other transmitters in the vicinity(e.g. minimizing false alarms due to interference from othertransmitters or emitters). Transmitter identification may be used tosupport networking and transmitter location and position determinationapplications as disclosed herein.

[0096] In other applications, a label that distinguishes one transmitterfrom another may itself serve as the ordered set of m data values thatis encoded to produce the symbol. In one such application, a transmitteris configured to transmit (e.g. at some predetermined interval) one ormore clusters corresponding to its label. The location of thetransmitter is then determined by comparing the arrival times of thecluster(s) at several (preferably three or more) receivers. An examplesystem uses one or more low-cost, low-power versions of such atransmitter as ‘smart tags’, e.g. for tracking the locations of boxes ina warehouse. Additional location and position determination techniquesand applications are discussed below.

[0097] In a basic modulation scheme according to an embodiment of theinvention, each time slot may have any number of bursts from zero to n.Therefore, each symbol may have 2^(np) different states. Such a schememay be applied to synchronous or asynchronous operations, and thetransmission channel may be wired, wireless, or optical (whether throughfree space or through fiber or another medium).

[0098] By varying such system parameters as the number of burstspermitted/required per time slot, the number of time slots per cluster,the number of frequency bands, whether the first time slot of a clusteris required to be occupied by at least one burst, and whether a clustermust include at least one burst in each frequency band, many differentschemes may be designed to suit many different situations. For example,a scheme that maximizes data transfer rate may be adopted for anoise-free application, while a scheme that maximizes symbol trackingperformance may be adopted for an asynchronous application, while ascheme that balances data transfer rate and error detection capabilitymay be adopted for another application. Various example schemes asapplied to the base implementation are described below.

[0099] In one such scheme, at least one burst occurs during each timeslot, such that no time slot within a symbol is empty. Such a scheme mayprovide a benefit in asynchronous operations (e.g. easier tracking). Inthis example, each symbol may have (2^(n)−1)^(p) different states.

[0100] In another scheme, one and only one burst occurs during each timeslot. Such a scheme may support asynchronous operations and/or offerreduced power output, for example, at the cost of reduced rate of datatransfer. Each symbol according to this example may have n^(p) differentstates.

[0101] In another scheme, up to n bursts occur during each time slot,and exactly one burst occurs per frequency band per cluster (in thisscheme, the number of time slots p is not less than the number offrequency bands n). The constraint of one burst per frequency band percluster may provide better performance in environments prone toreflection or multipath interference. Such a scheme may also be expectedto provide better error detection capability at the expense of a reduceddata transfer rate. Each symbol according to this example may have p^(n)different states (e.g. 100,000 different states for n=5 and p=10, or3125 different states for n=p=5).

[0102] In another scheme, one and only one burst occurs during each timeslot, and no more than one burst occurs per frequency band per cluster(in this scheme, the number of time slots p is not less than the numberof frequency bands n). Each symbol in this example may have n!/(n−p)!different states.

[0103] In one variation of the scheme above (one and only one burst pertime slot, and no more than one burst per frequency band per symbol),the first time slot of a cluster is unavailable for data transfer. Forexample, such a variation may be used to implement a logicalchannelization scheme in which the active frequency in the first timeslot identifies the particular logical channel over which the cluster isbeing transmitted. (Division of a physical channel into more than onelogical channel, and other techniques for such division, are discussedin more detail below.) Each symbol in this example may have up to(n−1)!/(n−p)! different data states.

[0104] In another scheme, no more than one burst occurs during each timeslot, and exactly one burst occurs per frequency band per cluster (inthis scheme, the number of time slots p is not less than the number offrequency bands n). This example scheme also includes the feature thatthe first time slot of each cluster is not empty; this feature (whichmay be especially useful in asynchronous applications) could be appliedto provide a relative time reference at the receiver. In this case, eachsymbol may have up to n(p−1)!/(p−n)! different states (e.g. 15,120different states for n=5 and p=10, or 120 different states for n=p=5).

[0105] In another scheme, no more than one burst occurs during each timeslot, no more than one burst occurs per frequency band per cluster, andthe first time slot of each cluster is not empty (in this scheme, thenumber of time slots p is not less than the number of frequency bandsn). In this case, the number of different states available for eachsymbol may be expressed as the sum over k (1≦k≦n) of the number ofclusters having bursts on exactly k frequency bands, or$\sum\limits_{k = 1}^{n}\quad {\begin{pmatrix}n \\k\end{pmatrix}k\frac{\quad {\left( {p - 1} \right)!}}{\left( {p - k} \right)!}}$

[0106] (e.g. 27,545 different states for n=5 and p=10, or 1045 differentstates for n=p=5).

[0107] In another scheme, up to n bursts may occur during each timeslot, exactly one burst occurs per frequency band per cluster, and thefirst time slot of each cluster is not empty (in this scheme, the numberof time slots p is not less than the number of frequency bands n). Inthis case, the number of different states available for each symbol maybe expressed as $\sum\limits_{k = 1}^{n}\quad {\begin{pmatrix}n \\k\end{pmatrix}\left( {p - 1} \right)^{n - k}}$

[0108] (e.g. 40,951 different states for n=5 and p=10, or 2101 differentstates for n=p=5).

[0109] In another scheme, up to n bursts may occur during each timeslot, no more than one burst occurs per frequency band per cluster, andthe first time slot of each cluster is not empty (in this scheme, thenumber of time slots p is not less than the number of frequency bandsn). In this case, the number of different states available for eachsymbol may be expressed as$\sum\limits_{k = 1}^{n}\quad {\begin{pmatrix}n \\k\end{pmatrix}{\sum\limits_{m = 1}^{k}\quad {\begin{pmatrix}k \\m\end{pmatrix}\left( {p - 1} \right)^{k - m}}}}$

[0110] (e.g. 61,051 different states form n=5 and p=10, or 4651different states for n=p=5).

[0111] In another scheme, up to n bursts may occur during each timeslot, no more than one burst occurs per frequency band per cluster, andeach cluster includes at least one burst (i.e. no cluster is empty) (inthis scheme, the number of time slots p is not less than the number offrequency bands n). In this case, the number of different statesavailable for each symbol may be expressed as$\sum\limits_{k = 1}^{n}\quad {\begin{pmatrix}n \\k\end{pmatrix}p^{k}}$

[0112] (e.g. 161,050 different states for n=5 and p=10, or 7775different states for n=p=5).

[0113] In another scheme, up to r (r≦n) bursts occur during each timeslot, exactly one burst occurs per frequency band per cluster, and thefirst time slot of each cluster is not empty (in this scheme, the numberof time slots p is not less than the number of frequency bands n). Inthis case, the number of different states available for each symbol maybe expressed as nc(r,n,p) using the following recursive formula:nc(r, nf, 1) = 1${{{nc}\left( {r,{nf},{ns}} \right)} = {\sum\limits_{\quad \underset{{M{({{ns} - 1})}} \geq {{nf} - s}}{s = {s1}}}^{{mm}{({r,{nf}})}}{\quad \begin{pmatrix}{nf} \\s\end{pmatrix}{{nc}\left( {M,{{nf} - s},{{ns} - 1}} \right)}}}},$

[0114] where the parameter nf denotes the number of frequency bandsstill unassigned in the cluster; the parameter ns denotes the number oftime slots remaining in the cluster; the constraint M(ns−1)≧(nf−s)requires that the product of the number of time slots that will remainand the maximum number of bursts per time slot is sufficiently large topermit assignment of the frequency bands that will remain; nc(A,B,C)denotes the number of combinations for up to A bursts per time slot, Bfrequency bands still unassigned in the cluster, and C time slotsremaining in the cluster; and the parameter s1 has the value${s1} = \left\{ {\begin{matrix}{0,\quad {{ns} < p}} \\{1,{{ns} = p}}\end{matrix}.} \right.$

[0115] For such a scheme in which each symbol has five n-tuples, thenumber of different states available for each symbol is indicated in thefollowing table as a function of n and r: r = 1 r = 2 r = 3 r = 4 r = 5n = 1 1 — — — — n = 2 8 9 — — — n = 3 36 60 61 — — n = 4 96 336 368  369— n = 5 120 1620 2060 2100 2101

[0116] In another scheme, exactly one burst occurs per frequency bandper cluster, the first time slot of each cluster is not empty, and fromone to r bursts occur during each time slot until no unassignedfrequency bands remain (in this scheme, the number of time slots p isnot less than the number of frequency bands n). In this case, the numberof different states available for each symbol may be expressed asnc(r,n,p) using the recursive formula above, except that s1=1 for anyvalue of ns.

[0117] Again, it is noted that the number of states per symbol indicatedfor the above examples assumes without limitation that each element ofeach n-tuple is binary-valued. Variations of such schemes in which oneor more elements of an n-tuple may have additional values arespecifically contemplated and enabled herein.

[0118] Many other schemes may be implemented according to suchprinciples. For example, in addition to variations to the baseimplementation as mentioned above, characteristics of such schemes mayinclude a minimum number of time slots between bursts on the samefrequency band (which minimum number may be different for differentfrequency bands), a maximum and/or minimum number of bursts during onetime slot, a minimum number of time slots per burst, a maximum and/orminimum number of consecutive empty time slots, etc. Depending on itsnature, a particular variation or characteristic may be applied duringencoding of the data set and/or during transmission of the symbol.

[0119] As noted above, the duration of an individual burst may be longeror shorter than the corresponding time slot. For timing purposes, it maybe desirable to synchronize the start of a burst with the start of thecorresponding time slot. However, other timing schemes are possible.

[0120] Bursts having one time relation that are transmitted overdifferent frequency bands may propagate through a dispersivecommunications channel such that the bursts have a different timerelation upon reception. For example, bursts at different frequencybands may be reflected differently in the environment, within thetransmitter, within the receiver, etc. In some applications, the timingof burst transmissions among the various n frequency bands may bemodified to adjust for expected propagation delays. For example, bursttransmissions may be timed such that bursts within the same time slotmay be expected to arrive at the receiver at substantially the sametime. Such modification may be based on a prior determination (e.g.calculation and/or measurement) and/or may be performed adaptivelyduring operation through a mechanism such as dynamic calibration. FIG.12 shows a diagram of one such application in which bursts in higherfrequency bands are transmitted earlier than bursts in lower frequencybands, according to an expected (e.g. calculated, calibrated, and/orobserved) difference in propagation delay.

[0121] In another example, the addition of a random (or pseudorandom)time perturbation may reduce peak power levels on a nominally periodictrain of symbols. FIG. 13 shows an effect of application of random delayperturbations (or ‘jitter’) to a simulated transmission of 100 clustersusing frequency bands centered at 3.5 and 4 GHz, repeated 20 times, withtwo bursts per cluster, burst duration 5 ns, quiet time period 40 ns,and symbol interval 50 ns. The bottom plot shows the spectrum thatoccurs when the same train of clusters is sent using a random delay of±10 ns.

[0122] In other implementations of a method according to an embodimentof the invention, each element of the series of n-tuples has one of qdistinct values, such that its value indicates an amplitude of thecorresponding burst. Such amplitude modulation may be added to a schemeas described or suggested above to increase the number of data valuesthat may be transferred during a designated time period. Addingamplitude modulation to the basic scheme in which each time slot mayhave any number of bursts from zero to n, for example, may result in asystem in which each symbol has q^(np) different possible states.

[0123] In further implementations of a method according to an embodimentof the invention, channel information may be encoded into intervalsbetween bursts and/or between clusters of bursts. FIG. 14 shows oneexample of such a scheme in which symbols for two different logicalchannels are transferred over the same physical channel at differenttimes. The upper diagram illustrates a sequence of clusters [A-1 andA-2] transmitted over a first time interval on the first logicalchannel, which is characterized by an interval of one time slot betweenconsecutive bursts. The lower diagram illustrates a sequence of clusters[B-1 and B-2] transmitted over a second time interval on the secondlogical channel, which is characterized by an interval of two time slotsbetween consecutive bursts. A receiver may be configured to identify theparticular logical channel associated with a received sequence ofclusters. Alternatively, a receiver may be configured to ignore all buta limited set (e.g. of one or more) of logical channels.

[0124] In some systems, the same physical channel may carry more thanone logical channel at the same time. For example, different logicalchannels that carry bursts during the same time interval may bedistinguished by the use of different frequencies and/or differentcombinations of frequencies. In a system in which transmission of burstsover different logical channels may be synchronized, each logicalchannel may also be distinguished by the number of time slots betweenconsecutive bursts of a cluster. FIG. 15 shows one such example in whichtwo logical channels are configured differently in terms of frequencyand timing. In another scheme, the number of time slots betweenconsecutive bursts of a cluster is a different prime number for eachlogical channel.

[0125] In the particular examples of FIGS. 14 and 15, the quiet timebetween clusters is the same on each logical channel, although in otherschemes this period may vary from one logical channel to another. In afurther example of a scheme including channelization, fewer than all ofthe pairs of consecutive bursts of a cluster (e.g. only the first andsecond bursts) are separated in time. In a yet further example of such ascheme, a width of one or more of the bursts of a cluster may identifythe corresponding logical channel.

[0126]FIG. 16 shows a block diagram of a transmitter 100 according to anembodiment of the invention. Encoder 200 receives a data signal S100that includes ordered data values (i.e. ordered in time and/or space)and outputs a symbol stream S150 based on signal S100 to signalgenerator 300. Specifically, encoder 200 maps ordered sets of m datavalues to corresponding symbols, each symbol including a series of pordered n-tuples. Based on symbol stream S150, signal generator 300outputs a modulated signal S200 that includes clusters of bursts (e.g.ultra-wideband bursts).

[0127]FIG. 17 shows a block diagram of an implementation 150 oftransmitter 100 that includes a signal launcher 450. Signal launcher450, which transfers modulated signal S200 to the transmission medium,may include one or more elements such as filters, power amplifiers, andimpedance-matching components (e.g. coils or transformers) orstructures.

[0128] For wireless transmission of clusters, signal launcher 450 mayalso include an antenna. In certain cases, the antenna may be embeddedinto a device that includes transmitter 100 or even integrated into apackage (e.g. a low-temperature co-fired ceramic package) that includescomponents of transmitter 100 and/or signal launcher 450.

[0129] For transmission of clusters through a conductive medium (e.g. awire, cable, or bus having one or more conductors, a conductivestructure, another conductive medium such as sea or ground water, or aseries of such conductors), signal launcher 450 may include one or moreelements such as components for electrostatic protection (e.g. diodes),current limiting (e.g. resistors), and/or direct-current blocking (e.g.capacitors).

[0130] For transmission of clusters through an optical medium (e.g. oneor more optical fibers or other transmissive structures, an atmosphere,a vacuum, or a series of such media), signal launcher 450 may includeone or more radiation sources controllable in accordance with theclusters to be transmitted such as a laser or laser diode or otherlight-emitting diode or semiconductor device.

[0131]FIG. 18 shows a block diagram of an implementation 110 oftransmitter 100 that includes an implementation 210 of encoder 200(having a mapper 250 and a serializer 400) and an implementation 301 ofsignal generator 300. Mapper 250 receives an m-unit parallel data signalS110 and produces a corresponding (n×p)-unit parallel encoded signalaccording to a predetermined mapping. For example, mapper 250 may beconstructed to receive an m-bit parallel data signal and produce acorresponding (n×p)-bit parallel encoded signal.

[0132] In one implementation, mapper 250 may include a lookup table thatmaps an m-unit input value to an n×p-unit output value. Alternatively,mapper 250 may include an array of combinational logic that executes asimilar predetermined mapping function. In another application, thepredetermined mapping function applied by mapper 250 may be changed fromtime to time (e.g. by downloading a new table or selecting between morethan one stored tables or arrays). For example, different channelconfigurations (e.g. different sets of frequency bands) may be allocatedin a dynamic fashion among implementations of transmitter 100 that sharethe same transmission medium.

[0133] Serializer 400 receives the (n×p)-unit parallel encoded signaland serializes the signal to output a corresponding n-unit (e.g. n-bit)implementation S160 of symbol stream S150 to signal generator 301 (e.g.at a data rate that is p or more times higher than the data rate of theparallel encoded signal). Signal generator 300 outputs a modulatedsignal S210 based on symbol stream S160.

[0134]FIG. 19 shows an implementation 410 of serializer 400 thatincludes n shift registers 412. Upon assertion of a common load signal(not shown), each shift register 412 stores a different p-unit coset ofthe n×p-unit encoded signal. In one example, the p units stored in eachshift register 412 are then shifted out (e.g. according to a commonclock signal) as a series of p n-tuples to signal generator 301.

[0135]FIG. 20 shows another implementation 420 of serializer 400 thatincludes an n×p-unit shift register 422. Upon assertion of a load signal(not shown), shift register 422 stores an n×p-unit string of values(e.g. as outputted by encoder 210). Each of the n-unit cosets of thisstring is then outputted as an n-unit value to signal generator 301according to a clock signal (not shown).

[0136]FIG. 21 shows a block diagram of an alternative implementation 120of transmitter 100. Encoder 220 outputs symbol stream S150 according todata signal S100 and a clock signal S300. Signal generator 300 receivessymbol stream S150 and outputs a corresponding modulated signal S200(e.g. as a series of clusters of ultra-wideband bursts).

[0137]FIG. 22 shows one implementation 222 of encoder 220. A counter 228receives clock signal S300 and outputs a count signal S350 having one ofp values. For example, count signal S350 may count up from 0 to (p−1),or down from (p−1) to 0, or may pass through p different states in someother fashion. Mapper 226 (e.g. a lookup table or combinatorial logicarray) receives m-unit data signal S110 and count signal S350 andoutputs a corresponding n-unit symbol stream S160 (e.g. to signalgenerator 301).

[0138] Signal generator 301 receives n-unit (e.g. n-bit) symbol streamS160 and outputs a series of clusters of bursts (e.g. ultra-widebandbursts) over n corresponding frequency bands. Each of the n frequencybands has a different center frequency. In one application, the nfrequency bands are separated from each other (e.g. by guard bands),although in other applications two or more of the bands may overlap eachother.

[0139] In one implementation, each unit of symbol stream S160 is a bitthat indicates whether or not a burst should be emitted (e.g. at apredetermined amplitude) over a corresponding frequency band during acorresponding time slot. In another implementation, a unit may have morethan two values, indicating one among a range of amplitudes at which thecorresponding burst should be emitted.

[0140] Signal generator 300 includes one or more burst generators, eachconfigured to generate a burst that may vary in duration from a portion(e.g. ½) of a cycle to several cycles. The time-domain profile of eachcycle of the burst may be a sine wave or some other waveform. In oneexample, a burst generator generates a burst as an impulse that isfiltered and/or amplified. Alternatively, a burst may be generated bygating a continuous-wave signal. For example, a burst generator mayinclude a broadband oscillator with controllable bandwidth. Signalgenerator 300 may include burst generators of the same configuration orburst generators according to two or more different configurations.Example configurations for a burst generator include the following:

[0141] 1) A circuit or device that produces a fast edge or pulse and isfollowed by a bandpass filter. The circuit or device that produces thefast edge or pulse generates a waveform with broadband spectral content,and the filter selects the frequency band over which transmission of theburst is desired. Examples of circuits or devices that produce a fastedge or pulse include high-speed logic gates such as ECL(emitter-coupled logic) and PECL (positive ECL). One suitableconfiguration may include a ring oscillator (e.g. as a free-runningoscillator with a gate on its output). Such circuits or devices may alsoinclude avalanche transistors, avalanche diodes, and/or step recoverydiodes. Examples of suitable filters may include cavity filters, surfaceacoustic wave (SAW) filters, discrete filters, transmission linefilters, and/or any other RF filter technique. In this case, the filtercontrols the relationship between energy and frequency within the band,and also establishes the roll-off profile of energy outside the band.

[0142] 2) A tunable oscillator followed by a switching device. Thetunable oscillator establishes the center frequency of the burst. Thetunable oscillator can be any tunable source of continuous-wave RFenergy, such as a voltage-controlled oscillator, a YIG (yttrium-indiumgamet)-tuned oscillator, a dielectric resonator oscillator, a backwardwave oscillator, and/or a oscillator circuit including a reflexklystron, magnetron, or Carcinotron. The switching device sets the widthof the burst, which defines the bandwidth of the spectral content.Suitable switching devices may include mixers, solid-state RF switches,laser-controlled RF switches, plasma-based RF switches, and/or switchesthat utilize an electron beam.

[0143] 3) A semiconductor solid-state oscillator that produces afrequency burst in response to a pulsed control voltage. The pulsedcontrol voltage may be provided by any circuit or device capable ofdelivering a pulse with the desired burst width and amplitude. In orderto provide a faster on/off transition, the control voltage may be biasedwith a DC level that is under the oscillation threshold, such thatapplication of the pulse raises the voltage over the oscillationthreshold and causes the device to oscillate for the duration of theapplied pulse. Examples of suitable solid-state oscillators may includeGunn devices, IMPATT (impact ionization avalanche transit time) diodes,TRAPATT (trapped plasma avalanche-triggered transit) diodes, and/orBARITT (barrier injection transit-time) diodes.

[0144] 4) A thermionic oscillator that produces a frequency burst inresponse to a pulsed control voltage. The pulsed control voltage may beprovided by any circuit or device capable of delivering a pulse with thedesired burst width and amplitude. Examples of control voltages includea grid voltage, a body voltage, or a reflector voltage. In order toprovide a faster on/off transition, the control voltage may be biasedwith a DC level that is under the oscillation threshold, such thatapplication of the pulse raises the voltage over the oscillationthreshold and causes the device to oscillate for the duration of theapplied pulse. Examples of suitable thermionic oscillators may includebackward wave oscillators, Carcinotrons, magnetrons, and/or reflexklystrons.

[0145]FIG. 23 shows an implementation 302 of signal generator 301 thatincludes a trigger generator 320 and a set of n burst generators 330. Asshown in FIG. 24, trigger generator 320 generates trigger pulses on nindependent trigger signals according to the elements of the n-tuples ofthe symbol to be transmitted. In this example, each of the n burstgenerators 330 is configured to emit a burst upon receiving a triggerpulse. In other implementations, a burst generator may be configured toemit a burst upon receiving a rising edge or a falling edge or upon someother event (which trigger pulse, edge, or other event may be electricaland/or optical). Also in this particular example, each burst generator330 is configured to emit bursts that occupy a different frequency bandthan bursts emitted by other burst generators 330. Each burst generator330 may be configured to emit bursts of constant time duration, or oneor more of generators 330 may be configured to emit bursts of varyingtime durations.

[0146]FIG. 25 illustrates that the outputs of burst generators 330 maybe summed (e.g. by summer 242 of implementation 452 of signal launcher450) before radiation (e.g. by an antenna) and may also be amplified ifdesired. As shown in FIG. 26, in another implementation 303 of signalgenerator 302, the outputs of burst generators 330 are summed (e.g. by asummer) within the signal generator. Also in another implementation, theoutputs of burst generators 330 are at baseband and may be upconverted(e.g. using a mixer and local oscillator) individually and/orcollectively (e.g. after summing).

[0147]FIG. 27 shows an implementation 304 of signal generator 300 thatincludes an oscillator 340 and a gate 368. Oscillator control logic 360,which may include a trigger generator such as trigger generator 320,outputs a frequency control signal S310 and an oscillator gate controlsignal S320 that are based on symbol stream S150. Frequency controlsignal S310 may include a set of trigger signals, e.g. as shown in FIG.25. Oscillator 340, which may be a tunable oscillator as describedherein, is tunable to emit waveforms over different frequency bands atdifferent times according to frequency control signal S310. Gate 368 mayinclude a switching device as described above, a mixer, a diode, oranother suitable gate. As shown in FIG. 28, the output of gate 368 maybe amplified (e.g. by a power amplifier 246 or by a controllable poweramplifier 248 as shown in FIG. 29) before radiation. Oscillator gatecontrol signal S320 may control such features as burst start time, burstduration, and burst polarity.

[0148] In some applications, an element of a symbol may indicate arising or falling frequency. In one such case, oscillator 340 iscontrolled (e.g. via frequency control signal S310) to emit a waveformwhose frequency changes accordingly. Such an implementation may alsoinclude a gate (e.g. gate 368) that is controlled (e.g. via oscillatorgate control signal S320) to output a burst having a correspondingrising or falling frequency. Such ‘chirping’ techniques may be used incombination with one or more modulation schemes as described above.

[0149] In some applications, a polarization of the transmitted signalmay be controlled according to symbol stream S150, e.g. within signallauncher 450. As shown in FIG. 29, an implementation 362 of oscillatorcontrol logic 360 may output a launcher control signal S330 to controlsuch parameters as burst amplitude, duration, and polarization.

[0150] It may be desirable to limit the spectral content of a burst. Forexample, reducing out-of-band emissions may support a more efficient useof bandwidth. Reducing out-of-band emissions may also be desired toavoid interference with other devices and/or may be required forregulatory compliance. While a filter may be used to modify the spectralcontent of a burst (as described above), in some applications it may bedesirable to modify the spectral content of a burst by controlling theshape of the burst in the time domain instead.

[0151] In one ideal system, the frequency spectrum of each burst isrectangular, and the bandwidth of the burst lies within the occupiedfrequency band. Within the frequency band, the power level is themaximum allowed by regulatory agencies; outside of the frequency band,the power level due to the burst is zero.

[0152] The frequency profile of a transmitted waveform may be controlledby controlling the time-dependent amplitude profile of the transmittedburst. If the time-dependent amplitude profile of the burst isrectangular, for example, the frequency content of the burst will have asine(f)/(f) profile (where f denotes frequency). In such cases, thebandwidth of the burst may extend into one or more adjacent frequencybands and may degrade performance. It may be desirable for thetime-dependent amplitude profile to have a sine(t)/(t) shape (where tdenotes time), so that a rectangular frequency profile may be created.

[0153] In a practical system, the time-dependent amplitude profile ofthe transmitted burst may have a shape that is an approximation to asine(t)/(t) function. The resulting frequency spectrum may have areduction in unintentional leakage of signal energy into an adjacentfrequency band (or out of the region of spectrum allocated by aregulatory agency) as compared to a case where a rectangular amplitudeprofile is utilized. Examples of time-dependent amplitude profiles thatmay be suitable for particular applications include raised cosine,Gaussian, and low-pass-filtered rectangular pulses.

[0154] The actual technique used to generate the desired time-dependantamplitude profile of the burst may depend on the technique used togenerate the burst. In many cases, for example, a control voltage withinthe waveform generator may be tailored to provide the desired tailoredburst. One such example is the use of a mixer to switch a CW waveform togenerate the desired burst. By low-pass filtering the control signalapplied to the mixer, one can obtain a tailored time-dependent amplitudeprofile and reduced leakage of energy into adjacent frequency bands.

[0155]FIG. 30 demonstrates that a square impulse in one of the time andfrequency domains corresponds to a waveform in the other domain that hasthe shape of a sinc function. (For example, the Fourier transform may beapplied to transform a waveform in one domain to the other domain.) FIG.31 illustrates an example of a spectrum resulting from the transmission(at three different frequencies) of bursts having square profiles in thetime domain. This figure demonstrates that transmitting a burst over onefrequency band may cause emissions in neighboring frequency bands. FIG.32 illustrates an example of a spectrum resulting from the transmission(at the same three frequencies) of bursts having sinc-shaped profiles inthe time domain. This figure demonstrates that shaping the time-domainprofile of a burst may reduce emissions in neighboring frequency bands.

[0156] These figures demonstrate that spectral shaping may be based ontime-domain control of a burst profile rather than (or in addition to)the use of burst-shaping filters. In certain burst generator examplesdescribed herein, the switch or applied voltage pulse may be used tocontrol the burst shape in the time domain, thereby controlling therelationship between energy and frequency within the band and alsoestablishing the roll-off profile of energy outside the band.

[0157]FIG. 33 shows a block diagram of a tunable oscillator 342according to an embodiment of the invention. Oscillator 342 may be usedas oscillator 340 in an implementation of signal generator 300 as shown,e.g., in FIGS. 27-29. In combination with a suitable switching device(e.g. a gate), oscillator 342 may also be used as burst generator 330 inother implementations of signal generator 300.

[0158] Oscillator 342 includes selectable delay lines 470, whichintroduce delays of different periods. Such delay lines may includeanalog delay elements (e.g. inductors, RC networks, long transmissionlines) and/or digital delay elements (e.g. inverters and/or other logicelements or gates). A common logic circuit 370 is coupled to the outputterminal of each selectable delay line 470. Common logic circuit 370,which includes one or more logic gates, changes the state of its outputsignal according to a state transition at one of its inputs and may ormay not invert the received state transition depending on the particularcircuit configuration. Each of selectable delay lines 470 is selectablevia frequency control signal S320 such that only one receives an outputsignal from common logic circuit 370 during any time period. It may bedesirable in some implementations to buffer the output of oscillator 342before connection of oscillator output signal S402 to a load.

[0159] In some implementations, a selectable delay line 470 may includea portion of the path that couples the selectable delay line to commonlogic circuit 370, with the length and/or character of such portionbeing designed to introduce a desired propagation delay or other effect.In other implementations, the delay (and/or the delay difference betweendelay lines) introduced by such paths may be considered negligible.

[0160] A control circuit or device (such as oscillator control logic360) provides frequency control signal S320 to control the frequency ofthe oscillator's output. For example, frequency control signal S320 maybe a function of an n-tuple that indicates a burst occupying aparticular frequency band. For at least some implementations ofoscillator 342, the frequency of oscillator output signal S402 may bechanged at every cycle of the oscillation.

[0161]FIG. 34 shows a block diagram of an implementation 344 ofoscillator 342. Each selectable delay line 472 includes an invertingselector portion 282 (e.g. a NOR gate) and a delay portion 292 having aneven number of inverters in series. Common logic circuit 372 is anoninverting selector (e.g. an OR gate). In this case, the lines offrequency control signal S322 are active low.

[0162]FIG. 35 shows a block diagram of an implementation 346 ofoscillator 342. Each selectable delay line 474 includes a noninvertingselector portion 284 (e.g. an AND gate) and a delay portion 292 havingan even number of inverters in series. Common logic circuit 374 is aninverting selector (e.g. a NOR gate). In this case, the lines offrequency control signal S324 are active high.

[0163] Many other configurations are possible for oscillator 342,including configurations in which each selectable delay line includes achain having an odd number of inverters in series. For example, FIG. 36shows such a configuration 348 that includes selectable delay lines 476having delay portions 294 (in this case, the lines of frequency controlsignal S322 are active low). The shortest path in an implementation ofoscillator 342 may include only three inversions, while the longest pathmay include an arbitrarily large odd number of inversions. Additionally,the number of different selectable delays in an implementation ofoscillator 342 may be arbitrarily large.

[0164]FIG. 37 shows a block diagram of an implementation 350 ofoscillator 342 in which an implementation 378 of common logic circuit370 includes a NAND gate and an inverter. In this example, eachselectable delay line 478 includes a selector portion 286 (e.g. a NANDgate) and a delay portion 292 that includes a generic (e.g. analogand/or digital) delay line.

[0165] In some implementations of oscillator 342, one or more delaypaths may be further selectable. For example, FIG. 38 shows animplementation 352 of oscillator 342 in which one of the delay pathsincludes two individual selectable delay lines 470.

[0166] Oscillators based on implementations of oscillator 342 asdescribed herein may also include oscillators that produce more than oneburst simultaneously, each such burst occupying a different frequencyband.

[0167] A frequency of an oscillator may change over time. For example,the delays introduced by the delay lines of oscillator 342 may change insome cases due to environmental factors, such as temperature or voltage,or to other factors such as aging or device-to-device variances. It maybe desirable to compensate for these variations, e.g. in order tomaintain a desired oscillation frequency.

[0168]FIG. 39 shows an implementation 356 of oscillator 342 thatincludes selectable adjustable delay lines 490. Each of selectableadjustable delay lines 490 may include a controllable delay element asdescribed in, e.g., any one of U.S. Pat. Nos. 5,646,519; 5,731,726; or6,054,884. Compensation circuit 495 controls a delay period of at leastone of selectable adjustable delay lines 490.

[0169]FIG. 40 shows a block diagram of an implementation 358 ofoscillator 342 that includes an implementation 496 of compensationcircuit 495. Divide-by-N circuit 380 scales the frequency of theoscillator output to match that of a reference frequency oscillator 382.A phase-locked loop (or digital locked loop) 384 compares the twofrequencies and outputs a signal (e.g. a voltage) according to adifference in frequency or phase between them. One or moredigital-to-analog converters (DACs) and/or controllable voltagereferences 386 may be included to convert a digital difference signalinto an analog signal to control a characteristic of one or more of theadjustable delay lines 492. A DAC or controllable reference may bededicated to one delay line or may control more than one delay line. TheDACs or controllable references may also serve to sample and hold thedifference signal until a subsequent compensation operation. In anotherimplementation, one or more of the adjustable delay lines are controlleddigitally.

[0170]FIG. 41 shows a block diagram of an implementation 359 ofoscillator 342 that includes an alternate implementation 498 ofcompensation circuit 495. This circuit includes an additional delay line388 that is fabricated to react to environmental changes in the same wayas the adjustable delay lines 492. The adjustable delay lines are thencontrolled according to a frequency or phase error in the additionaldelay line 388.

[0171]FIG. 42 shows a block diagram of an implementation 354 ofoscillator 340 that may be used in place of oscillator 342, e.g. in manyof the applications described herein. In this implementation,multiplexer 290 applied an implementation S328 of frequency controlsignal S320 to provide selection between the various delay lines 480,which may be adjustable (e.g. by a compensation circuit as describedherein) but need not include selector portions.

[0172] In some applications, it may be acceptable to run oscillator 340continuously. In other applications, it may be desirable to reduce powerconsumption by, e.g., turning on oscillator 340 (or a portion thereof,such as a compensation circuit) only a short period before transmitting.

[0173] In some implementations of oscillator 342, an oscillator outputsignal may be tapped off for signal launch at more than one location.For example, tap off can occur at a junction where all signals arecombined, or could occur outside of junctions for each signal in whichthe signals may or may not be later combined.

[0174]FIG. 43 shows a block diagram of an implementation 3591 ofoscillator 342. When all of the delay lines are disabled (in thisexample, by holding all lines of frequency control signal S320 high),the oscillator section (here, gates 710, 720, and 730) within commonlogic circuit 376 may be set to run freely (in this example, with bothlines of oscillator gate control signal S329 being high). When a signallaunch is desired, frequency control signal S320 selects the desireddelay line and both lines of oscillator gate control signal S329 are setlow, forming a circuit including the selected delay line and output gate740 to oscillate at the desired frequency. The lines of oscillator gatecontrol signal S329 may be individually timed, or one line may be used.Similarly, the line or lines of oscillator gate control signal S329 maybe linked to (e.g. may provide timing for or may be derived from)frequency control signal S320 or may be individually timed (e.g.depending upon factors such as gate setup and hold times and concernssuch as avoiding spurious outputs). A configuration as in oscillator3591 may reduce transients due to oscillator start-up time by separatinga free-running oscillator section from the output (e.g. from the signallauncher), so that this oscillator section may be continuously runningbetween bursts or may be started-up at some time prior to the signalbeing launched.

[0175] In some applications, it may be desirable to filter the output ofoscillator 360 (e.g. to remove unwanted harmonics). Examples of suitablefilters may include cavity filters, surface acoustic wave (SAW) filters,discrete filters, transmission line filters, and/or any other RF filtertechnique.

[0176] Implementations of oscillator 360 as described above may befabricated (e.g. in whole or in part) in application-specific integratedcircuits (ASICs) using one or more known techniques such as ECL, PECL,CMOS, or BiCMOS and materials such as SiGe, GaAs, SiC, GaN, ‘strainedsilicon’, etc.

[0177]FIG. 44 shows a receiver 400 according to an embodiment of theinvention. Signal detector 410 receives a received signal (e.g. afteramplification and/or filtering) and outputs an ordered series ofn-tuples. Decoder 420 receives the ordered series of n-tuples andoutputs a corresponding ordered set of data values. Decoder 420 may alsoperform digital signal processing operations on the series of n-tuples(e.g. filtering operations).

[0178]FIG. 45 shows a block diagram of a burst detector 430 suitable foruse in signal detector 410. Filter 440 (e.g. a bandpass filter) passesenergy within a particular frequency band. Edge detector 450 detects arising edge of a signal received within the corresponding frequencyband. Signal detector 410 may include a parallel arrangement of severalburst detectors, each configured to detect bursts on a differentfrequency band.

[0179]FIG. 46 shows a block diagram of an implementation 450 a of edgedetector 450. In this example, the envelope detector is a square-lawdevice. For high-frequency applications, for example, the envelopedetector may be a tunneling diode or similar device. The baseband outputof the envelope detector is amplified (e.g. by baseband amplifier 520)and digitized (e.g. by analog-to-digital converter (ADC) 530).

[0180] In its simplest form, digitization of the baseband signal may beperformed by comparison of the signal with a reference voltage (e.g.thresholding). For example, FIG. 47 shows a block diagram of such an ADC532 including a comparator 540. Depending on the particular application,other suitable ADCs may include multi-bit parallel-encoding (flash),successive-approximation, dual-slope, digital-ramp,delta-sigma-modulation, or other configurations.

[0181]FIG. 48 shows an implementation 401 of receiver 400 that includesan implementation 412 of signal detector 410. This signal detectorincludes a parallel arrangement of implementations 432 of burst detector430. As shown in this example, a burst detector 430 may include otherprocessing blocks such as low-noise amplifiers (LNAs). A receiver mayalso include an LNA between the antenna and processing circuitry.

[0182]FIG. 49 shows a block diagram of another implementation 450 b ofedge detector 450. In this example, a correlator 610 receives thefiltered signal and correlates it with a template to produce acorresponding baseband signal.

[0183]FIG. 50 shows an implementation 402 of receiver 400 that includesan implementation 414 of signal detector 410. This signal detectorincludes a parallel arrangement of implementations 434 of burst detector430 that include correlators 610, each of which may apply a differenttemplate to their input signals. In this case, each burst detector 434also includes a LNA 560 upstream of the correlator that serves as afilter.

[0184] As the operating speed of ADCs increases, it is also contemplatedto sample the incoming signal directly and filter it after digitization.One such receiver is shown in FIG. 51. In one such implementation, thedigitized output is filtered (e.g. by decoder 420) to determine theactivity over time on each frequency band. In another implementation,successive fast Fourier transforms are performed in time on thedigitized output, and the activity on each individual frequency band isdetermined from the resulting spectral information.

[0185] It is also possible to divide the signal into different sectionsof the spectrum and then to downconvert each section separately. Afterdownconversion (e.g. using a mixer 620 and local oscillator 630 at thedesired intermediate frequency, which may differ from one frequency bandto another), the bursts may be detected using edge detection or thesignal may be sampled directly with an ADC. FIG. 52 shows a blockdiagram of an implementation 404 of receiver 400 that includes edgedetectors, and FIG. 53 shows a block diagram of an implementation 405 ofreceiver 400 that samples each signal directly using an ADC.

[0186] In some applications, it may be desirable to downconvert thereceived signal to an intermediate frequency (e.g. by mixing with alocal oscillator signal) before performing further processing asdescribed above. FIG. 54 shows one such implementation 406 of receiver400 in which the downconverted signal is divided into separatefrequencies before edge detection. FIG. 55 shows another implementationin which the downconverted signal is divided into separate frequenciesbefore correlation. FIG. 56 shows a further implementation in which thedownconverted and filtered signal is digitized directly.

[0187]FIG. 57 shows a block diagram of an implementation 4090 ofreceiver 400 in which an intermediate frequency signal is separated intodifferent frequency bands before a second downconversion and edgedetection. FIG. 58 shows a block diagram of another implementation 4091in which the twice-downconverted signals are digitized and filtered. Insome applications, an increase in signal-to-noise ratio may be achievedby performing gating of the received signal (e.g. in combination with areceiver configuration as described herein).

[0188] In some applications, it may be desirable for a receiver asdescribed herein to apply a timestamp to one or more received clustersor to otherwise note the order and/or time of arrival of clusters. Forexample, such information may be applied during decoding of the receivedsymbols and/or may be applied to overcome multipath interference.Information regarding the relative time between clusters may also beused to detect empty clusters (such a technique may also be applied atthe time-slot scale to detect empty time slots). For noting order ofarrival only, the timestamp may be generated using a counter whose stateis updated (e.g. incremented) at each noted event (e.g. clusterarrival). For noting time of arrival, the timestamp may be generatedusing a clock (e.g. a counter whose state is updated according to anoscillator). For relative measurements between events, it may not benecessary to synchronize such a clock to a reference or to otherwisetake account of the clock's initial state.

[0189] At least some of the techniques for data transfer as disclosedherein may be embedded into highly scaleable implementations. Forexample, such a technique may be applied to wireless replacement ofcables for transmission of content and/or control data. In a low-endapplication, this technique may be implemented to replace a cable (e.g.a Universal Serial Bus or USB cable) linking a computer to a low-cost,low-data-rate peripheral such as a computer mouse, keyboard, or handheldgaming controller. In a mid-range application, the technique may be usedto replace a cable carrying video information from a computer to amonitor. In a high-end application, the technique may be scaled toreplace one or more of the cables that carry high-fidelity video andaudio information (e.g. from a receiver, a set-top box, or DVD (DigitalVersatile Disc) player) to a high-definition television display andaudio system.

[0190] Other applications that may vary in cost and performancerequirements to those noted above include wireless computer networking,wireless transfer of audio data (e.g. as one or more datastreams and/orfiles, and in formats such as sampled (e.g. WAV) and/or compressed (e.g.MP3)), wireless transfer of image data (e.g. from a digital still cameraor other device including one or more CCD or CMOS sensors, and inuncompressed or compressed (e.g. JPEG, JPEG2000, PNG) format), andwireless replacement of cables transmitting such formats or protocols asEthernet, USB, IEEE 1394, S-video, NTSC, PAL, SECAM, and VoIP (Voiceover IP).

[0191] In addition to many office and consumer entertainmentapplications, such cable replacement may be applied to control systemsin industry and at home (e.g. thermostatic control); in automobiles andother vehicles; and in aircraft applications (e.g. for control systemsand also to support networking applications such as passenger e-mail).Therefore, systems, methods, and apparatus for data transfer asdisclosed herein may be implemented to suit a wide range of differentlatency, performance, and cost requirements.

[0192] One problem that may be encountered when using existing methodsof wireless data transfer is an inability (e.g. insufficient datathroughput rate) to support the data rate or latency requirements for ademanding application such as real-time video display. As noted above,systems, methods, and apparatus for data transfer as disclosed hereinmay be implemented to transfer data at very high rates. In one suchapplication, a set-top box includes an apparatus for data transfer asdisclosed herein which may be used to transmit a video signal wirelesslyto a television display (e.g. a flat-panel display). One benefit thatmay be realized from a very high data rate in such an application is anability to update the displayed picture (e.g. in response to the userchanging the channel) in real time, rather than after a lag as might besuffered in a low-data-rate system that requires buffering to maintainthe displayed picture.

[0193] Signal source identification mechanisms may be applied withinsystems, methods, and apparatus for data transfer as disclosed herein tosupport networking applications. An identifier such as a serial numbermay be hard-coded into a transmitter or transceiver (e.g. duringmanufacture or installation), or the identifier may be assigned orupdated by the application during use. The identifier may be transmittedin the same manner as other data to be transferred (e.g. within aprotocol or other higher-layer abstraction), or the identifier may bedistinguished from other data within the physical layer by usingfeatures discussed herein such as logical channelization and/or unusedsymbol states. Communications applications in which sourceidentification may be useful include directing communications withinpiconets, mesh networks, and multihop networks (e.g. includingrepeaters); distributed sensor networks for industry and military;encrypted and other secure communications; and selective or exclusivecommunication between data sources (e.g. a computer or PDA) andperipherals (e.g. a printer).

[0194] Applications for systems, methods, and apparatus for datatransfer as disclosed herein may include location and positiondetermination tasks. These tasks may include ranging and triangulationoperations. A ranging signal may include a burst, a stream of bursts atdifferent frequencies and/or different times, or a cluster or group ofclusters. Ultra-wideband signals having extremely short bursts (e.g.durations of one nanosecond or less) are especially well-suited to suchapplications because the shortness of the bursts corresponds (underideal conditions) to high spatial resolutions (e.g. down to the order ofone centimeter). Better spatial resolution may also be achieved bytransmitting the ranging signal over a wide frequency range (e.g.including bursts over more rather than fewer frequency bands). It may bedesirable for a ranging signal to include signal source identificationinformation (e.g., as described above), especially in an environmentthat includes potential interferers such as other transmitters.

[0195] In one example of a ranging operation, a first transceivertransmits a ranging signal. A second transceiver detects the signal andtransmits a response (e.g. a ranging signal that may include informationsuch as the second transceiver's location). The first transceiverdetects the response, notes the round-trip time of flight, removes aknown latency value (e.g. the propagation time within the circuits),divides by two to remove the bidirectional component, and divides by thespeed of light to determine the distance between the two transceivers. Atriangulation (or trilateration) operation may then be performed bycombining the distances obtained from at least three such rangingoperations (i.e. between the first transceiver and at least three othertransceivers having known locations) to determine the firsttransceiver's location.

[0196] In another example of a ranging operation, a first transmittertransmits a ranging signal that is received by three or more receivers.The times of arrival of the signal at each receiver are transmitted to aprocessing unit (e.g. via a network), which combines the various timesof arrival and corresponding receiver locations in a triangulation (ortrilateration) operation to determine the transmitter's location. It maybe desirable in this case for the receivers to be synchronized to acommon clock.

[0197] In a variation of the ranging operation above, the ranging signalincludes a signal source identifier. Each receiver timestamps thereceived ranging signal according to the time of arrival and transmitsthe timestamped signal (including the source identifier) to theprocessing unit. Such a technique may be used to support location andposition determination for multiple transmitters. Transmitter locationand position determination may also be performed within a multihopnetwork such that the processing unit is several hops removed from thetransmitter.

[0198] At least some of the systems, apparatus, and methods of datatransfer as disclosed herein may be applied to sensor networks. In sucha network, a possibly large number of sensors is deployed across anarea, with sensed data being returned (possibly relayed via multihop) toa processing unit. Each sensor is configured to sense an environmentalcondition such as gas concentration, radiation level at one or morefrequencies or ranges (e.g. charged particle, X-ray, visible light,infrared), temperature, pressure, sound, vibration, etc. A sensor mayinclude an analog-to-digital converter for converting data relating tothe sensed condition from analog to digital form.

[0199] A sensor network as described herein may be used for temperaturemonitoring within a facility, for an intruder alert system, or forremote monitoring of activity in an area (e.g. for military purposes).The processing unit, which calculates the state of the network from thecollective sensed data, may act accordingly or may convey the stateinformation to another unit.

[0200] Additionally, use of methods and apparatus for data transfer asdescribed herein may include applications requiring very low cost,robustness to interference and/or multipath, low probability forintercept and/or detection, and/or sensor applications (e.g. networkedor peer-to-peer). For example, low-cost sensors may permit vastdeployments for either tagging or distributed feedback systems forcommercial, industrial, and military applications. Interference andmultipath robustness may be especially useful for deployments inindustrial settings and military scenarios where jamming (intentional orunintentional) and/or reflections are likely. Low probability forintercept (both in terms of implementing special symbol codes and interms of possible operations at low emission levels) and low probabilityfor detection are critical components of covert military or sensitiveusages.

[0201] The foregoing presentation of the described embodiments isprovided to enable any person skilled in the art to make or use theinvention as claimed. Various modifications to these embodiments arepossible, and the generic principles presented herein may be applied toother embodiments as well. For example, implementations of a receiver asdescribed herein may also be applied to receive signals transmittedusing chirping techniques as described herein. Additionally, theprinciples described herein may be applied to communications over wired,wireless, and/or optical transmission channels.

[0202] The invention may be implemented in part or in whole as ahard-wired circuit and/or as a circuit configuration fabricated into anapplication-specific integrated circuit. The invention may also beimplemented in part or in whole as a firmware program loaded intonon-volatile storage (e.g. ROM or flash or battery-backup RAM) or asoftware program loaded from or into a data storage medium (for example,a read-only or rewritable medium such as a semiconductor orferromagnetic memory (e.g. ROM, programmable ROM, dynamic RAM, staticRAM, or flash RAM); or a magnetic, optical, or phase-change medium (e.g.a floppy, hard, or CD or DVD disk)) as machine-readable code, such codebeing instructions executable by an array of logic elements such as amicroprocessor or other digital signal processing unit or an FPGA.

[0203] In some cases, for example, the design architecture for a timedivision multiple frequency (TDMF) modulation technique according to anembodiment of the invention may be realized in an application-specificintegrated circuit (ASIC). Such a design may be implemented as astand-alone packaged device, or embedded as a core in a larger systemASIC. Features of an architecture according to certain such embodimentsof the invention lend themselves well to an ASIC implementation thatenables low cost, low power, and/or high volume production. Embodimentsof the invention may include designs that are scalable with evolvingsemiconductor technologies, enabling increased performance objectivesand expanded applications. In some cases an entire such architecture maybe implemented in a single semiconductor process, although even in thesecases it may be possible to transfer the design to multiplesemiconductor technologies rather than to depend on a singlesemiconductor process.

[0204] Thus, the present invention is not intended to be limited to theembodiments shown above but rather is to be accorded the widest scopeconsistent with the principles and novel features disclosed in anyfashion herein.

What is claimed is:
 1. A method of data transmission, said methodcomprising: encoding an ordered set of m data values to produce acorresponding series of ordered n-tuples; and according to the series ofordered n-tuples, transmitting a plurality of bursts, each burstoccupying at least one of a plurality n of frequency bands, wherein, foreach of the plurality of bursts, a frequency band occupied by the burstis indicated by the order within its n-tuple of an element correspondingto the burst, and wherein a bandwidth of at least one of the pluralityof bursts is at least two percent of the center frequency of the burst.2. The method of data transmission according to claim 1, wherein, foreach of the plurality of bursts, the burst corresponds to one element ofthe series of ordered n-tuples.
 3. The method of data transmissionaccording to claim 2, wherein, for each of the plurality of bursts, atime of transmission of the burst relative to the rest of the pluralityof bursts is indicated by the order, within the series of orderedn-tuples, of the n-tuple that includes the element corresponding to theburst.
 4. The method of data transmission according to claim 2, wherein,for each of the plurality of bursts, a time of transmission of the burstrelative to the rest of the plurality of bursts occurs according to anexpected propagation delay of the burst.
 5. The method of datatransmission according to claim 1, wherein, for each of the plurality ofbursts, a timing of the burst relative to the rest of the plurality ofbursts is indicated by the order, within the series of ordered n-tuples,of an n-tuple that includes an element corresponding to the burst. 6.The method of data transmission according to claim 1, wherein at leastone of the plurality of bursts corresponds to a plurality of the m datavalues.
 7. The method of data transmission according to claim 1, whereina bandwidth of at least one of the plurality of bursts is at least tenpercent of the center frequency of the burst.
 8. The method of datatransmission according to claim 1, wherein a bandwidth of at least oneof the plurality of bursts is at least twenty percent of the centerfrequency of the burst.
 9. The method of data transmission according toclaim 1, wherein a duration of at least one of the plurality of burstsis less than one cycle.
 10. The method of data transmission according toclaim 1, wherein a duration of at least one of the plurality of burstsis less than five cycles.
 11. The method of data transmission accordingto claim 1, wherein a duration of at least one of the plurality ofbursts is less than ten cycles.
 12. The method of data transmissionaccording to claim 1, wherein each among the series of ordered n-tuplescorresponds to one among a series of time periods, and wherein each ofthe series of time periods has a different start time, and wherein, foreach of the plurality of bursts, the time period during which the burstis launched is indicated by the location within the series of n-tuplesof an n-tuple that includes an element corresponding to the burst. 13.The method of data transmission according to claim 12, wherein duringeach time period, no more than one of the plurality of bursts islaunched.
 14. The method of data transmission according to claim 1,wherein for each frequency band occupied by one of the plurality ofbursts, no other one of the plurality of bursts occupies the frequencyband.
 15. The method of data transmission according to claim 1, whereinthe series of n-tuples comprises a series of binary n-tuples, andwherein said transmitting occurs according to the series of n-tuplessuch that in response to a high value of an element of a binary n-tuple,a burst occupies the frequency band corresponding to the order of theelement within its n-tuple during a time period corresponding to then-tuple, and in response to a low value of an element of a binaryn-tuple, a burst is not transmitted on the frequency band correspondingto the order of the element within its n-tuple during a time periodcorresponding to the n-tuple.
 16. The method of data transmissionaccording to claim 1, wherein said transmitting includes transmittingthe plurality of bursts over an optical fiber.
 17. The method of datatransmission according to claim 1, wherein said transmitting includestransmitting the plurality of bursts over a cable having at least oneconductor.
 18. The method of data transmission according to claim 1,wherein said transmitting includes transmitting the plurality of burstsover a wireless transmission channel.
 19. The method of datatransmission according to claim 1, wherein the number of orderedn-tuples in the series is greater than the number n of frequency bands.20. The method of data transmission according to claim 1, wherein thenumber n of frequency bands is greater than the number of orderedn-tuples in the series.
 21. The method of data transmission according toclaim 1, wherein at least one among the plurality of bursts has atime-domain profile that is more sinc-shaped than rectangular and afrequency-domain profile that is more rectangular than sinc-shaped. 22.The method of data transmission according to claim 1, wherein saidplurality of bursts includes a first burst occupying one of theplurality of frequency bands and a second burst occupying a differentone of the plurality of frequency bands, and wherein at least onefrequency point exists at which the amplitude of the first burst iswithin twenty decibels of the maximum amplitude of the first burst andat which the amplitude of the second burst is within twenty decibels ofthe maximum amplitude of the second burst.
 23. The method of datatransmission according to claim 1, wherein at least one frequency pointexists at which the amplitude of the first burst is within ten decibelsof the maximum amplitude of the first burst and at which the amplitudeof the second burst is within ten decibels of the maximum amplitude ofthe second burst.
 24. The method of data transmission according to claim1, said method further comprising: receiving the plurality of bursts ata first location and at a first time of arrival; generating a firsttimestamp corresponding to the first time of arrival; receiving theplurality of bursts at a second location and at a second time ofarrival; generating a second timestamp corresponding to the second timeof arrival; and calculating at least one among a position and a locationbased at least on the first timestamp and the second timestamp.
 25. Themethod of data transmission according to claim 1, said method furthercomprising: transmitting a second plurality of bursts during a firsttime period, each burst occupying at least one among a plurality n offrequency bands; receiving a third plurality of bursts during a secondtime period, each burst occupying at least one among a plurality n offrequency bands; and calculating a distance based on a differencebetween the first and second time periods.
 26. A transmitter comprising:means for encoding an ordered set of m data values to produce acorresponding series of ordered n-tuples; and means for transmitting,according to the series of ordered n-tuples, a plurality of bursts, eachburst occupying at least one of a plurality n of frequency bands,wherein, for each of the plurality of bursts, a frequency band occupiedby the burst is indicated by the order within its n-tuple of an elementcorresponding to the burst, and wherein a bandwidth of at least one ofthe plurality of bursts is at least two percent of the center frequencyof the burst.
 27. The transmitter according to claim 26, wherein, foreach of the plurality of bursts, a time of transmission of the burstrelative to the rest of the plurality of bursts is indicated by theorder, within the series of ordered n-tuples, of an n-tuple thatincludes an element corresponding to the burst.
 28. The transmitteraccording to claim 26, wherein at least one of the plurality of burstscorresponds to a plurality of the m data values.
 29. The transmitteraccording to claim 26, wherein a bandwidth of at least one of theplurality of bursts is at least twenty percent of the center frequencyof the burst.
 30. The transmitter according to claim 26, wherein aduration of at least one of the plurality of bursts is less than tencycles.
 31. The transmitter according to claim 26, wherein each amongthe series of ordered n-tuples corresponds to one among a series of timeperiods, and wherein each of the series of time periods has a differentstart time, and wherein, for each of the plurality of bursts, the timeperiod during which the burst is launched is indicated by the locationwithin the series of n-tuples of an n-tuple that includes an elementcorresponding to the burst.
 32. The transmitter according to claim 26,wherein said transmitting includes transmitting the plurality of burstsover a wireless transmission channel.
 33. A data storage medium havingmachine-readable code stored thereon, the machine-readable codecomprising instructions executable by an array of logic elements, theinstructions defining a method of data transmission, said methodcomprising: encoding an ordered set of m data values to produce acorresponding series of ordered n-tuples; and according to the series ofordered n-tuples, transmitting a plurality of bursts, each burstoccupying at least one of a plurality n of frequency bands, wherein, foreach of the plurality of bursts, a frequency band occupied by the burstis indicated by the order within its n-tuple of an element correspondingto the burst, and wherein a bandwidth of at least one of the pluralityof bursts is at least two percent of the center frequency of the burst.34. The data storage medium according to claim 33, wherein, for each ofthe plurality of bursts, a time of transmission of the burst relative tothe rest of the plurality of bursts is indicated by the order, withinthe series of ordered n-tuples, of an n-tuple that includes an elementcorresponding to the burst.
 35. The data storage medium according toclaim 33, wherein at least one of the plurality of bursts corresponds toa plurality of the m data values.
 36. The data storage medium accordingto claim 33, wherein a bandwidth of at least one of the plurality ofbursts is at least twenty percent of the center frequency of the burst.37. The data storage medium according to claim 33, wherein a duration ofat least one of the plurality of bursts is less than ten cycles.
 38. Thedata storage medium according to claim 33, wherein each among the seriesof ordered n-tuples corresponds to one among a series of time periods,and wherein each of the series of time periods has a different starttime, and wherein, for each of the plurality of bursts, the time periodduring which the burst is launched is indicated by the location withinthe series of n-tuples of an n-tuple that includes an elementcorresponding to the burst.
 39. The data storage medium according toclaim 33, wherein said transmitting includes transmitting the pluralityof bursts over a wireless transmission channel.
 40. A transmittercomprising: an encoder configured to receive an ordered set of m datavalues and to produce a corresponding series of ordered n-tuples; and asignal generator configured to transmit, according to the series ofordered n-tuples, a plurality of bursts, each burst occupying at leastone of a plurality n of frequency bands, wherein, for each of theplurality of bursts, a frequency band occupied by the burst is indicatedby the order within its n-tuple of an element corresponding to theburst, and wherein a bandwidth of at least one of the plurality ofbursts is at least two percent of the center frequency of the burst. 41.The transmitter according to claim 40, wherein the encoder includes alookup table configured to associate the ordered set of m data valueswith an ordered set including the corresponding series of orderedn-tuples.
 42. The transmitter according to claim 40, wherein the encoderincludes a combinatorial logic array configured to receive the orderedset of m data values and to produce an ordered set including thecorresponding series of ordered n-tuples.
 43. The transmitter accordingto claim 40, wherein said encoder includes a serializer configured tooutput one among the series of ordered n-tuples over a correspondingperiod of time and to output another among the series of orderedn-tuples over a different corresponding period of time.
 44. Thetransmitter according to claim 40, wherein said encoder is configured tooutput one among the series of ordered n-tuples over a first period oftime and another among the series of ordered n-tuples over a secondperiod of time different from the first period of time.
 45. Thetransmitter according to claim 40, wherein said signal generatorincludes a trigger generator configured to generate a plurality oftrigger events according to the series of ordered n-tuples.
 46. Thetransmitter according to claim 40, wherein said signal generatorincludes a plurality of burst generators, wherein each of the pluralityof burst generators is configured to receive a trigger event and togenerate at least one of the plurality of bursts according to thetrigger event.
 47. The transmitter according to claim 40, wherein saidsignal generator includes a plurality of burst generators, wherein eachof the plurality of burst generators corresponds to one of the pluralityn of frequency bands and is configured to generate bursts which occupythat frequency band.
 48. The transmitter according to claim 40, saidtransmitter further comprising a signal launcher configured to receivethe plurality of bursts and to transmit the plurality of bursts over atransmission medium, wherein said signal launcher includes a poweramplifier.
 49. The transmitter according to claim 48, wherein saidsignal launcher includes an antenna.
 50. The transmitter according toclaim 48, wherein said signal launcher includes a light-emitting diode.51. The transmitter according to claim 48, wherein said signal launcherincludes a filter.
 52. The transmitter according to claim 40, whereinsaid signal generator includes an oscillator configured to output asignal over a selectable one of at least two of the plurality n offrequency bands.
 53. The transmitter according to claim 40, wherein saidsignal generator includes a gate configured to control an amplitude of asignal over one of the plurality n of frequency bands to produce aburst.
 54. The transmitter according to claim 40, wherein, for each ofthe plurality of bursts, a time of transmission of the burst relative tothe rest of the plurality of bursts is indicated by the order, withinthe series of ordered n-tuples, of an n-tuple that includes an elementcorresponding to the burst.
 55. The transmitter according to claim 40,wherein at least one of the plurality of bursts corresponds to aplurality of the m data values.
 56. The transmitter according to claim40, wherein a bandwidth of at least one of the plurality of bursts is atleast twenty percent of the center frequency of the burst.
 57. Thetransmitter according to claim 40, wherein a duration of at least one ofthe plurality of bursts is less than ten cycles.
 58. The transmitteraccording to claim 40, wherein each among the series of ordered n-tuplescorresponds to one among a series of time periods, and wherein each ofthe series of time periods has a different start time, and wherein, foreach of the plurality of bursts, the time period during which the burstis launched is indicated by the location within the series of n-tuplesof an n-tuple that includes an element corresponding to the burst. 59.The transmitter according to claim 40, said transmitter furthercomprising a sensor configured to sense an environmental condition andto output the ordered set of m data values according to the sensedenvironmental condition.
 60. A method of data reception, said methodcomprising: receiving a plurality of bursts, each burst occupying atleast one of a plurality n of frequency bands, obtaining a series ofordered n-tuples based on the plurality of bursts; and decoding theseries of ordered n-tuples to produce an ordered set of m data values,wherein, for each of the plurality of bursts, the order within itsn-tuple of an element corresponding to the burst is indicated by afrequency band occupied by the burst, and wherein a bandwidth of atleast one of the plurality of bursts is at least two percent of thecenter frequency of the burst.
 61. The method of data receptionaccording to claim 60, wherein, for each of the plurality of bursts, theorder, within the series of ordered n-tuples, of an n-tuple thatincludes an element corresponding to the burst is indicated by a timingof the burst relative to the rest of the plurality of bursts.
 62. Themethod of data reception according to claim 60, wherein at least one ofthe plurality of bursts corresponds to a plurality of the m data values.63. The method of data reception according to claim 60, wherein abandwidth of at least one of the plurality of bursts is at least twentypercent of the center frequency of the burst.
 64. The method of datareception according to claim 60, wherein a duration of at least one ofthe plurality of bursts is less than ten cycles.
 65. The method of datareception according to claim 60, wherein each among the series ofordered n-tuples corresponds to one among a series of time periods, andwherein each of the series of time periods has a different start time,and wherein, for each of the plurality of bursts, the location withinthe series of n-tuples of an n-tuple that includes an elementcorresponding to the burst is indicated by a timing of the burstrelative to the rest of the plurality of bursts.
 66. The method of datareception according to claim 60, wherein said receiving includesreceiving the plurality of bursts over a wireless transmission channel.67. A receiver comprising: a signal detector configured to receive asignal including a plurality of bursts, each burst occupying at leastone of a plurality n of frequency bands, and to output a series ofordered n-tuples based on the plurality of bursts; and a decoderconfigured to produce an ordered set of m data values from the series ofordered n-tuples, wherein the signal detector is configured to output,for each of the plurality of bursts, an element corresponding to theburst such that an order of the element within its n-tuple correspondsto a frequency band occupied by the burst, and wherein a bandwidth of atleast one of the plurality of bursts is at least two percent of thecenter frequency of the burst.
 68. The receiver according to claim 67,wherein the signal detector includes at least one edge detectorconfigured to detect an edge of a received burst.
 69. The receiveraccording to claim 67, wherein the signal detector includes at least oneenvelope detector configured to detect an envelope of a received burst.70. The receiver according to claim 67, wherein the signal detectorincludes at least one comparator configured to detect a feature of areceived burst.
 71. The receiver according to claim 67, wherein thesignal detector includes at least one correlator configured to detect areceived burst based on a correlation of a template with at least aportion of the received signal.
 72. The receiver according to claim 67,wherein the signal detector includes at least one mixer configured tochange a frequency of at least a portion of the received signal.
 73. Thereceiver according to claim 67, wherein the signal detector includes atleast one filter configured to select at least a portion of acorresponding one of the plurality n of frequency bands.
 74. Thereceiver according to claim 67, wherein, for each of the plurality ofbursts, the order, within the series of ordered n-tuples, of an n-tuplethat includes an element corresponding to the burst is indicated by atiming of the burst relative to the rest of the plurality of bursts. 75.The receiver according to claim 67, wherein at least one of theplurality of bursts corresponds to a plurality of the m data values. 76.The receiver according to claim 67, wherein a bandwidth of at least oneof the plurality of bursts is at least twenty percent of the centerfrequency of the burst.
 77. The receiver according to claim 67, whereina duration of at least one of the plurality of bursts is less than tencycles.
 78. A method of data transmission, said method comprising:receiving a data signal including ordered data values; encoding orderedsets of m data values to produce corresponding series of orderedn-tuples; and according to each series of ordered n-tuples, transmittinga plurality of bursts, each burst occupying at least one of a pluralityn of frequency bands, wherein, for each burst of each plurality ofbursts, a frequency band occupied by the burst is indicated by the orderwithin its n-tuple of an element corresponding to the burst, and whereina bandwidth of at least one burst of each plurality of bursts is atleast two percent of the center frequency of the burst.
 79. The methodof data transmission according to claim 78, wherein the data signalincludes video data.
 80. The method of data transmission according toclaim 78, wherein a data throughput rate of said transmitting is atleast equal to a data rate of said data signal.
 81. The method of datatransmission according to claim 78, wherein the data signal includesdata representing at least one image.
 82. The method of datatransmission according to claim 78, wherein the data signal includesaudio data.
 83. The method of data transmission according to claim 78,wherein said transmitting includes transmitting each plurality of burstsover a wireless transmission channel.
 84. The method of datatransmission according to claim 83, wherein said receiving includesreceiving the data signal through a Universal Serial Bus (USB) port. 85.A system including: a plurality of transmitters, each of the pluralityof transmitters comprising: a sensor configured to sense anenvironmental condition and to output a ordered set of m data valuesaccording to the sensed environmental condition; an encoder configuredto receive the ordered set of m data values and to produce acorresponding series of ordered n-tuples; and a signal generatorconfigured to transmit, according to the series of ordered n-tuples, aplurality of bursts, each burst occupying at least one of a plurality nof frequency bands, such that, for each of the plurality of bursts, afrequency band occupied by the burst is indicated by the order withinits n-tuple of an element corresponding to the burst; and a receiverconfigured to receive the plurality of bursts from each transmitter, todecode the corresponding ordered sets of m data values, and to associateeach among the ordered sets of m data values with a location of thecorresponding transmitter, wherein a bandwidth of at least one of eachplurality of bursts is at least two percent of the center frequency ofthe burst.
 86. The system according to claim 85, wherein at least oneamong said plurality of transmitters is further configured to transmit asecond plurality of bursts indicating one among a location and aposition of said transmitter.